[ItaniumDemangle][test] Add test-cases for ref-qualified member pointer parameters
I noticed that there are test-cases that are commented out. But the
manglings for them seem to be impossible to generate from valid C++. I
added two test-cases generated from following C++ program:
```
struct X {
int func() const && { return 5; }
const int &&func2() { return 5; }
const int &&func3(const int &x) volatile { return 5; }
};
void f(int (X::*)() const &&, int const && (X::*)(),
int const && (X::*)(const int &) volatile) {}
int main() {
f(&X::func, &X::func2, &X::func3);
return 0;
}
```
NOKEYCHECK=True
GitOrigin-RevId: 46f18b7c6febe75b2cc0095f2227d935c14f70f2
1 file changed
